Haven't seen anyone attempt this specific setup yet, but TL;DR, if you have a spare Xbox storage expansion card lying around and have since moved over to PC, it is possible to use the card as storage on your PC.
It was known that they work with CF Express USB card readers, but any post I've seen required physically trimming off plastic from the expansion card. This was a PCIE CF Express adapter off Amazon. This sits flush and works without any drivers or anything. It also "clicks" in like a DS or Switch cart so it's pretty secure.
Ultimately this is not cost effective unless you already have the hardware sitting around, but hey if you cancelled Game Pass or moved over to PC, it's potentially a cheap way to expand your storage if you have one of these just laying around or underutilized.
Here's the adapter I used. The full PCIE slot one I used is out of stock, but there's still a low profile one:
Here's a similar one, untested:
Interestingly there is an m.2 adapter, can't vouch for whether this works, but I don't see why it wouldn't.